Gas turbine machines have many forms and applications. The two most popular and known are turbo-jet engines and the type of turbine engines that supply mechanical power. These turbine engines are built today mainly for aeronautical and military applications, and therefore designed to very high standards and are produced only in relatively small series.
As a result of this situation, turbine engines are so highly priced that they are prohibitive for most civilian and industrial markets. Accordingly, at present there is no extensive usage of turbines in civilian installations, apart from a few back up and emergency turbine generators in power stations. In the below 100 HP size, for which the military has almost no use, there is an acute lack of gas turbines and it is in this range of size that civilian applications would be desirable.
Under these conditions of construction and of use of gas turbines, the building and use of small units has been excluded a priori for economical reasons.
Technical problems cause a decrease of the mechanical efficiency of gas turbine engines in relation to their size. Generally, it may be said that small turbine engines of the same type are less efficient than big ones. But besides their use as prime movers, in which capacity they are rather inefficient, gas turbine machines can fulfil a range of other duties. As hot gas generators, for example, their efficiency is very high, whilst other roles include blowers, compressors, combined heaters and compressors, as well as many other applications. It is in these duties, because of compactness, high efficiency, reliability, and long service life combined with a multi-fuel capacity that gas turbines can provide an attractive alternative solution to existing installations.
For all these reasons, it would be highly desirable to have small gas turbine units--mainly for the production of hot gases for industrial--purposes which should be produceable in reasonably large series at an ultimate customer's worksite, at reasonable cost, with proper spare parts availability.